INTROdUCTION• Optical fibers are long, thin strands of very pure glass usually 120 µm in diameter. They are arranged in bundles called optical cables and used to transmit light signals over long distances.
PARTS OF OPTICAL FIBER• Core – thin glass center of the fiber where light travels.• Cladding – outer optical material surrounding the core.• Buffer Coating – plastic coating that protects the fiber.
TRANSMISSION OF LIghT ThROUgh OPTICAL FIBERS• Total Internal Reflection
TOTAL INTERNAL REFLECTION • The angle of the light is always greater than the critical angle. • Cladding does not absorb any light from the core. • The extent that the signal degrades depends upon the purity of the glass and the wavelength of the transmitted light.
FIBER OPTICS SySTEMS hAS Transmitter Optical Fiber Optical Regenerator Optical Receiver
TyPES OF OPTICAL FIBERSOptical fibers come in two types:• Single-mode fibers• Multi-mode fibers1. Step Indexed2. Graded Indexed
SINgLE-MOdE FIBERS• Single-mode fibers are used to transmit one signal per fiber (used in telephone and cable TV). They have small core (9 microns in diameter) and transmit infra-red light from laser.
MULTI-MOdE FIBERS• Multi-mode fibers are used to transmit many signals per fiber (used in computer networks). They have larger cores (62.5 microns in diameter) and transmit infra-red light from LED.
AdvANTAgES• Less Expensive• Enormous Potential Bandwidth• High Carrying Capacity• Less Signal Degradation• Electrical Isolation• Low Power• Signal Security• Small Size & Light Weight• System Reliability & Ease of Maintenance• Ruggedness & Flexibility• Low Transmission Loss
dISAdvANTAgES• Fiber optics are that the cables are expensive to install.• The termination of a fiber optic cable is complex and requires special tools.• They are more fragile than coaxial cable.
RESEARCh QUESTIONS• What can fiber optics do for us in the future? – Improve our communication – Faster internet connection• What would the Internet look like if this could happen? – Streaming capabilities – Download capabilities• What is being done to make this transition happen? – Government action – Private Companies at work